This invention generally relates to a washer seal for a cam braking system bushing assembly and more particularly to a washer seal that transmits axial forces between components in the braking system, prevents contaminants from entering the bushing assembly and acts as a secondary lubricant sealing system to contain lubricant within the cam brake bushing assembly.
Bushing assemblies are used to support a camshaft in a brake housing. As known, the brake camshaft drives a brake cam to actuate the brake. A secondary purpose of the bushing assembly is to allow for lubrication of the camshaft so that it can freely rotate.
Known cam bushing assemblies include a bushing retainer having an aperture and a bushing disposed within the aperture. This design allows for efficient lubrication flow around the camshaft.
Washers have been used in combination with cam bushing retainers. Typically, these washers have been simple metal disks, which do not conform to the specific size and location of adjacent components. The purpose of the washer is to maintain appropriate distances between cam brake components and to transmit axial forces between the camshaft and bushing retainer. However, the design of washers used with cam bushing retainers has not always been effective at preventing damage to the bushing assembly because the washer is not secured to the bushing assembly. Further, the washer does not act as a secondary sealing system. Lubrication could leak around the washer because the washer is not connected to the retainer.
An ineffective washer design allows dirt and debris to enter the bushing environment. The introduction of debris into the bushing environment contributes to increased wear of the bushing components and the camshaft. Increased wear of the components translates into frequent maintenance, high repair costs, and decreased life expectancy of all cam braking system components.
The cam bushing washer seal assembly of the present invention overcomes the above problems with known cam bushing washers. In general terms, the disclosed washer seal assembly covers and protects a bushing assembly in a cam braking system by sealingly conforming to the bushing retainer. The washer seal is made from a metal washer bonded to a flexible material. The flexible material is preferably a neoprene elastomeric compound. The washer seal assembly is directly connected to the bushing assembly by being deformed radially outwardly to engage the bushing assembly. The washer seal assembly is preferably used with a cam bushing assembly in a cam braking system.
There are several functions of the washer seal assembly. One function of the washer seal assembly is to provide a shield to minimize intrusion of debris and other contaminants around the camshaft support bushing and its associated seals. Dirt and contaminants cause damage to the bushing, its seals and ultimately the camshaft, thereby increasing the amount of required maintenance of those parts and the frequency of replacement. Therefore, it is desirable to minimize the amount of contaminants introduced to the bushing environment. The washer seal serves this purpose. Use of the washer seal decreases the wear of the bushing and the seals, therefore, increasing the useful life of bushing components and the camshaft.
The washer seal also provides for relative motion between the camshaft and the bushing retainer while transmitting axial forces between the camshaft and the bushing assembly. The washer seal isolates the bushing assembly from the camshaft, therefore, preventing wear on the bushing assembly due to camshaft rotation.
Further, the washer seal assembly acts as a secondary sealing system that supplements the primary sealing system. In other words, the washer seal provides seals around the camshaft and the bushing assembly to contain the lubrication within the bushing assembly.